The present invention relates to a part mounting apparatus for mounting parts on a substrate and a part mounting method.
A known part mounting apparatus for mounting an electronic part having the shape of a film (hereinafter referred to as xe2x80x9cfilm electronic partxe2x80x9d) on a glass substrate has been used as part mounting apparatus for fabricating a flat panel display, such as a liquid crystal panel.
Such a part mounting apparatus recognizes the positional relation between a glass substrate conveyed by a substrate conveying unit, and a film electronic part conveyed by a part conveying unit by means of an imaging device and an image processing device, and locate the film electronic part at a predetermined position in an edge portion of the glass substrate on the basis of position data provided by the image processing device. Subsequently, a pressing tool presses the film electronic part against the edge portion of the glass substrate supported on a backup tool to connect the film electronic part to the edge portion of the glass substrate with a connecting member, such as an anisotropic conductive film or the like.
There is the trend toward greater glass substrates on which film electronic parts are mounted. Greater glass substrates are subject to deformation, such as warping. When an edge portion of a warped glass substrate is supported on the backup tool and the pressing tool presses the film electronic part against the edge portion of the glass substrate, the film electronic part slides on the glass substrate, whereby film electronic part mounting accuracy is reduced greatly.
There has been proposed a correcting method employing a correcting unit for correcting a warped glass substrate to bring the surface of the warped glass substrate to a level before mounting a film electronic part on an edge portion of the glass substrate.
FIG. 7 shows a part mounting apparatus for carrying out such a correcting method. Referring to FIG. 7, a substrate conveying unit 60 conveys a glass substrate 31 to a mounting position. Upon the arrival of the glass substrate 31 at the mounting position, a backup tool 63 rises to support an edge portion of the glass substrate 31 from below. Subsequently, a correcting unit 65 descends and depresses the glass substrate 31 supported on the backup tool 63 to correct a warp in the glass substrate 31. Then, a pressing tool 64 descends to attach a film electronic part 32 with a connecting member 33, such as an anisotropic conductive film, to the flattened surface of the edge portion of the glass substrate 31. A conveyor stage 61 included in the substrate conveying unit 60 is provided with a plurality of vertically compressible suction pads 62 to hold the glass substrate 31 on the conveyor stage 61 by suction.
However, the foregoing conventional method is incapable of satisfactorily correcting a large warp and local warps in the glass substrate 31 because of restrictions on the position where the correcting unit 65 presses the glass substrate 31 and the pressure exerted by the correcting unit 65 (FIG. 8).
The foregoing method holds the glass substrate 31 by the plurality of suction pads 62 of the substrate conveying unit 60. Therefore, the positional relation between the glass substrate 31 and the conveyor stage 61 is apt to change when the correcting unit 65 presses the glass substrate 31, whereby the accuracy of mounting the film electronic part 32 on the glass substrate 31 is apt to decrease.
Moreover, the throughput of final products decreases because the foregoing method needs to drive the correcting unit 65 every time the film electronic part is mounted on the edge portion of the glass substrate 31.
The present invention has been made in view of those problems and it is therefore an object of the present invention to provide a part mounting apparatus and a part mounting method capable of accurately and efficiently mounting a part, such as a film electronic part or the like, on a substrate, such as a glass substrate or the like.
According to the present invention, a part mounting apparatus for mounting an electronic part on a substrate includes a substrate conveying unit that conveys a substrate; a backup tool that supports an edge portion of a substrate conveyed by the substrate conveying unit; and a pressing tool disposed on the opposite side of the backup tool with respect to the substrate; wherein the substrate conveying unit includes a conveyor stage, a plurality of suction pads disposed in an edge portion of the conveyor stage to hold the substrate by suction from below, and a plurality of supporting members disposed in the edge portion of the conveyor stage to support the substrate thereon in cooperation with the suction pads.
Preferably, the suction pads and the supporting members are arranged alternately. The plurality of suction pads may be arranged along the edges of the conveyor stage, and the supporting members may be disposed on the outer side of the suction pads nearer to the edges with respect to the suction pads and adjacently to the suction pads, or on an inner side of the suction pads farther from the edges with respect to the suction pads and adjacently to the suction pads. Preferably, the part mounting apparatus further includes a suction adjusting mechanism capable of adjusting suctions (attractions) to be applied by the suction pads to the substrate according to the state of deformation of the substrate. Preferably, the part mounting apparatus further includes a deformation measuring device for measuring the state of deformation of the substrate, and a controller for controlling the respective suctions of the suction pads of the substrate conveying unit on the basis of measured data provided by the measuring device. Preferably, the part mounting apparatus includes a position adjusting mechanism for adjusting the respective positions of the suction pads and the supporting embers according to the state of deformation of the substrate. Preferably, the substrate conveying unit is provided with an adjusting mechanism for adjusting the respective heights of the supporting members from the conveyor stage.
According to the present invention, a part mounting method of mounting an electronic part on a substrate includes the steps of: holding a substrate on a conveyor stage by a plurality of suction pads and a plurality of supporting members disposed on the conveyor stage; measuring the state of deformation of the substrate held on the conveyor stage; adjusting at least suctions to be applied by the suction pads to the substrate, the respective positions of the suction pads on the conveyor stage, the respective positions of the supporting members on the conveyor stage or the respective heights of the supporting members according to the measured state of deformation of the substrate; conveying the substrate held on the conveyor stage to a mounting position by moving the conveyor stage; and mounting a part on the substrate conveyed to the mounting position.
Thus, the present invention disposes the plurality of suction pads and the plurality of supporting members in the edge portion of the conveyor stage, and corrects the deformation, such as a warp, in the substrate by a suction exerted vertically on the substrate by the suction pads and a reaction force exerted vertically on the substrate by the supporting members. Therefore, a large warp and local warps in the substrate can be effectively corrected, the surface of the substrate can be brought to a level and the substrate can be held at a level corresponding to that of the upper ends of the supporting members and, consequently, the part can be accurately and efficiently mounted on the substrate